Optical information storage medium

ABSTRACT

An optical information storage medium includes a lead-in area, a lead-out area, and a user data area between the lead-in and lead-out areas and in which user data is recorded. Pits are formed in the lead-in area, the user data area, and the lead-out area, and a track pitch in all or a portion of the lead-in area is different from a track pitch in the remaining area of the optical information storage medium.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/242,886, filed Oct. 5, 2005, currently pending, which is acontinuation of U.S. patent application Ser. No. 10/633,564, filed Aug.5, 2003, which issued as U.S. Pat. No. 7,272,106, which claims thebenefit of Korean Patent Application No. 2002-54756, filed on Sep. 10,2002 in the Korean Intellectual Property Office, the disclosures ofwhich are incorporated herein in their entirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an optical information storage medium,and more particularly, to an optical information storage medium in whicha track pitch in all or a portion of a lead-in area is different from atrack pitch in remaining areas of the optical information storage mediumso that the reliability of reproduction of important optical informationstorage medium-related information can be improved.

2. Description of the Related Art

Optical discs are generally used as information storage media of opticalpickup devices, which record information on and/or reproduce informationfrom the optical discs without contacting the optical discs. Opticaldiscs are classified as either compact discs (CDs) or digital versatilediscs (DVDs) according to their information recording capacity. CDs andDVDs further include 650 MB CD-Rs, CD-RWs, 4.7 GB DVD+RWs, DVD-randomaccess memories (DVD-RAMs), DVD-R, DVD-rewritables (DVD-RWs), and soforth. Read-only discs include 650 MB CDs, 4.7 GB DVD-ROMs, and thelike. Furthermore, high-density digital versatile discs (HD-DVDs) havebeen developed which have a recording capacity of 20 GB or more.

Various methods of increasing the recording capacity of optical discshave been studied. One method of increasing the recording capacity is toreduce a size of an optical spot focused on an optical disc. To reducethe size of the optical spot, the wavelength of a laser light sourceshould be shortened or a numerical aperture (NA) of an objective lensshould be increased. Further, the track pitch of the optical disc shouldbe reduced. The track pitch refers to a minimum distance measured from acentral line of one track to a central line of an adjacent track.

FIG. 1 illustrates the structure of a conventional DVD-ROM 110. TheDVD-ROM 110 includes a user data area 105 in which user data isrecorded. A lead-in area 100 is formed inside the user data area 105. Alead-out area 110 which is formed outside the user data area 105. Datais recorded as dots in the lead-in area 100, the user data area 105, andthe lead-out area 110. Also, the track pitch is 0.74 μm in the lead-inarea 100, the user data area 105, and the lead-out area 110.

The track pitch tends to be reduced when increasing the recordingcapacity. However, since an optical spot focused on a track may reach anadjacent track, the possibility that cross-talk will occur becomes highas the track pitch is reduced. If cross-talk occurs, an abnormalreproduction signal is output. Thus, as the track pitch is reduced,there is an increase in abnormal reproductions of information.

In particular, if information is abnormally reproduced from an area inwhich is recorded important information in recording and/or reproducingdata, this abnormal reproduction may gravely affect a recording and/orreproduction efficiency of a disc. Accordingly, the track pitch isrequired to be adjusted in accordance with an increase in the recordingcapacity of a storage medium and the importance of data.

SUMMARY OF THE INVENTION

The present invention provides an optical information storage medium inwhich a track pitch in an area in which is recorded important opticalinformation storage medium-related information is different from a trackpitch in a user data area in which is recorded user data so that theefficiency and reliability of the reproduction of data can be improved.

Additional aspects and/or advantages of the invention will be set forthin part in the description which follows and, in part, will be obviousfrom the description, or may be learned by practice of the invention.

According to an aspect of the present invention, an optical informationstorage medium includes a lead-in area, a lead-out area that is formedoutside the the lead-in area, and a user data area disposed between thelead-in and lead-out areas and in which user data is recorded where pitsare formed in first tracks of the lead-in area, second tracks ofremaining area including the user data area, and the lead-out area, anda track pitch of between adjacent first tracks in all or a portion ofthe lead-in area is different from a track pitch between adjacent secondand/or third tracks in the remaining areas of the optical informationstorage medium.

It is preferable, but not required, that the first track pitch isgreater than the second track pitch in the remaining area of the opticalinformation storage medium.

According to an aspect of the invention, the lead-in area includes anarea in which optical information storage medium-related information isrecorded and an area in which copy protection information is recorded.

It is preferable, but not required, that the first track pitch in atleast one of the areas of the lead-in area is greater than the secondtrack pitch in the remaining area of the optical information storagemedium.

It is preferable, but not required, that a ratio of tracking errorsignals detected in the area having the first track pitch to trackingerror signals detected in the area having the second track pitch is 1.5or more.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or other features and advantages of the present inventionwill become more apparent and more readily appreciated by describing indetail exemplary embodiments thereof with reference to the accompanyingdrawings in which:

FIG. 1 illustrates the schematic structure of a conventional DVD-ROM;

FIG. 2 illustrates the schematic structure of an optical informationstorage medium according to an embodiment of the present invention;

FIG. 3A illustrates a phase tracking error signal (a differential phasedetect (DPD) signal) when a track pitch is 0.32 μm;

FIG. 3B illustrates a phase tracking error signal (a DPD signal) when atrack pitch is 0.35 μm; and

FIG. 4 is a block diagram of a recording and/or reproducing apparatusaccording to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the present embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to the like elementsthroughout. The embodiments are described below in order to explain thepresent invention by referring to the figures.

Referring to FIG. 2, an optical information storage medium 1000according to an embodiment of the present invention includes a user dataarea 15, a lead-in area 10 which is formed inside the user data area 15,and a lead-out area 20 which is formed outside the user data area 15 andthe lead-in area 10. A first track pitch in all or a portion of thelead-in area 10 is different from a second track pitch in remainingareas of the optical information storage medium 1000 including the userdata and lead-out areas 15, 20.

The lead-in area 10 includes areas in which is recorded important datain reproduction from the optical information storage medium. Examples ofthe important data include optical information storage medium-relatedinformation, which is recorded in area 10 a, and copy protectioninformation, which is recorded in area 10 b. The optical informationstorage medium-related information contains information on the type ofstorage medium (such as whether the medium 1000 is a recordable disc,write-once disc, or a read-only disc), information on the number ofrecording layers, information on the recording speed, and information onthe size of the optical information storage medium 1000 (disc).

It is preferable, but not required, that a track pitch in at least oneof the areas 10 a and 10 b is the first track pitch which is greaterthan the second track pitch in the remaining areas except the areas 10 aand 10 b. It is understood that additional important information inreproduction from the optical information storage medium 1000 may berecorded, and the track pitch in the entire lead-in area 10 may be thefirst track pitch which is greater than the second track pitch in theremaining areas of the optical information storage medium 1000.

The optical information storage medium according to an embodiment of thepresent invention is read-only optical information storage medium. Thepits are formed everywhere in the lead-in area 10, the user data area15, and the lead-out area 20. The pits are formed in a substrate inadvance when manufacturing the read-only embodiment of the opticalinformation storage medium 1000. If data is recorded as the pits, thepits can be formed in the lead-in area 10 and the user data area 15without stopping a process of forming the pits. Thus, a process ofmanufacturing an optical information storage medium can be simplifiedand the time required for performing the process can be reduced.

One method of performing a tracking operation using the pits is adifferential phase detect (DPD) method. For example, the DPD method isused to realize a track servo depending on the phase shift of an opticalspot focused on a quarter photodetector. The DPD method is well known,and thus will not be described in detail herein. According to the DPDmethod, when track pitches on the optical information storage medium aredifferent, an output tracking error signals (such as differential phasetracking error signals) are different. For example, FIG. 3A illustratesa DPD signal when the track pitch is 0.32 μm, and FIG. 3B illustrates aDPD signal when the track pitch is 0.35 μm. Here, when the samereproduction power is output, the amplitude of a phase tracking errorsignal (a DPD signal) in the track pitch of 0.32 μm was about 1.46V. Incontrast, the amplitude of the DPD signal in the track pitch of 0.35 μmwas about 2.31V. Thus, the amplitude of the DPD signal when the trackpitch is larger increased about 1.58 times the amplitude of the DPDsignal when the track pitch is smaller. As can be seen in FIGS. 3A and3B, as the track pitch increased, the amplitude of the DPD signal isincreased. As the amplitude of the DPD signal is increased, an errordetecting efficiency is improved. Thus, the reproduction efficiency andreliability are improved as the track pitch increased.

According to the result of simulations, it was found that, when thetrack pitch TP in the area 10 a or the area 10 b is I and the trackpitch TP in the remaining areas of the optical information storagemedium is II, it is preferable, but not required, that a ratio of atracking error signal, particularly, a phase tracking error signal, toeach of the track pitches TP is 1.5 or more as expressed by equation 1set forth below: $\begin{matrix}{\frac{{Tracking}\quad{Error}\quad{Signal}_{{TP} = I}}{{Tracking}\quad{Error}\quad{Signal}_{{TP} = {II}}} \geq 1.5} & (1)\end{matrix}$

The optical information storage medium according to embodiments of thepresent invention can be applied to an optical information storagemedium having one or more recording surfaces. In other words, if theoptical information storage medium has a plurality of recordingsurfaces, the track pitch in all or a portion of a lead-in area of eachof the plurality of recording surfaces can be greater than the trackpitch in the remaining area of each of the plurality of recordingsurfaces. Accordingly, the track pitch in a portion of the lead-in areain which important information is recorded can be greater than the trackpitch in the remaining area of the optical information storage medium sothat the reproduction reliability of the important information can beincreased.

While not specifically so limited, it is understood that the informationstorage medium can include the CD-Rs, CD-RWs, DVD-RWs, DVD-RAMs,DVD+RWs, as well as next generation high definition DVDs, such asBlu-ray discs and Advanced Optical Discs (AODs). Further, it isunderstood the information storage medium need not include lead-inand/or lead-out areas.

FIG. 4 is a block diagram of a recording and/or reproducing apparatusaccording to an embodiment of the present invention. Referring to FIG.4, the recording apparatus includes a recording/reading unit 1001, acontroller 1002, and a memory 1003. The recording/reading unit 1001records data on a disc 1000, which is an embodiment of an informationstorage medium 1000 of the present invention, and reads the data fromthe disc 1000. The controller 1002 records and reproduces data fromtracks having first and second track pitches according to the presentinvention as set forth above in relation to FIGS. 2 through 3B.

While not required in all aspects, it is understood that the controller1002 can be computer implementing the method using a computer programencoded on a computer readable medium. The computer can be implementedas a chip having firmware, or can be a general or special purposecomputer programmable to perform the method.

In addition, it is understood that, in order to achieve a recordingcapacity of several dozen gigabytes, the recording/reading unit 1001could include a low wavelength, high numerical aperture type unit usableto record dozens of gigabytes of data on the disc 1000. Examples of suchunits include, but are not limited to, those units using lightwavelengths of 405 nm and having numerical apertures of 0.85, thoseunits compatible with Blu-ray discs, and/or those units compatible withAdvanced Optical Discs (AOD).

As described above, in an optical information storage medium accordingto the present invention, the track pitch in an area, such as an opticalinformation storage medium-related information area or a copy protectioninformation area of a lead-in area, in which important information isrecorded, is greater than the track pitch in the remaining areas of theoptical information storage medium. Thus, reliable reproduction of theimportant information can be achieved without deteriorating a signal dueto cross-talk occurring between adjacent tracks during reproduction ofthe important information.

While the present invention has been particularly shown and describedwith reference to exemplary embodiments thereof, it will be understoodby those of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the present invention as defined by the following claims andequivalents thereof.

1. An optical information storage medium for use with a recording and/orreproducing apparatus, the storage medium comprising: a lead-in areahaving a first subarea and a second subarea, the first subareacomprising optical information storage medium-related informationincluding a number of information recording layers and which theapparatus uses to determine the number of information recording layersfor the optical information storage medium; a lead-out area; and a dataarea formed between the lead-in and lead-out areas and in whichpredetermined data is recorded wherein: the first subarea has a firsttrack pitch between adjacent tracks of the first subarea, at least oneof the second subarea and the data area has a second track pitch betweenadjacent tracks of the one of the second subarea and the data area, andthe first track pitch is greater than the second track pitch.
 2. Anapparatus to optically transfer data with respect to an opticalinformation storage medium that comprises a lead-in area having firstsubarea and second subarea, a lead-out area, and a data area formedbetween the lead-in and lead-out areas and in which user data isrecorded, the apparatus comprising: an optical unit to emit light totransfer data with respect to the optical information storage medium;and a controller to control the optical unit to transfer first data withrespect to the first subarea having a first track pitch between adjacenttracks of the first subarea, to transfer second data with respect to atleast one of the second subarea and the data area having a second trackpitch between adjacent tracks of the one of the second subarea and thedata area, and to obtain from the first subarea optical informationstorage medium-related information including a number of informationrecording layers of the optical information storage medium, wherein thefirst track pitch is greater than the second track pitch.